Justin Smith’s streak ends; WR Manningham is active

The 49ers All-Pro defensive tackle is inactive because of what the team is terming an elbow injury he sustained in last week’s win over the Patriots. Four-year veteran Ricky Jean Francois, 26, will make his fourth career start in place of Smith against an offense that ranks third in the NFL in rushing yards per game (160.7). The Seahawks arrive as just the fifth team in NFL history – and first since the 1963 Chargers – to score 50 points in back-to-back games.

Meanwhile, wide receiver Mario Manningham will play after missing the past two games with a shoulder injury. With Manningham back in the lineup, first-round pick A.J. Jenkins will be inactive for the 12th time this season. The 49ers’ other inactives include linebacker Clark Haggans (shoulder), quarterback Scott Tolzien, safety Trenton Robinson and running back Jewel Hampton.

Linebacker Cam Johnson, a seventh-round pick, is active and is expected to make his NFL debut on special teams.

** Seattle cornerbacks Marcus Trufant and Walter Thurmond are both inactive because of hamstring injuries, leaving the Seahawks without three of its top four cornerbacks. Starter Brandon Browner is serving a four-game suspension.

Rookie Jeremy Lane, a sixth-round pick, will make his second career start alongside Richard Sherman. Rookie J.R. Sweezy, a seventh-round pick, will also make his second career start in place of injured starter John Moffitt.